In recent years, in a display apparatus having a liquid crystal panel, a thin film transistor (TFT) has been mainly used. Specifically an a-Si TFT using amorphous silicon for a channel region or a P-Si TFT using a polysilicon (poly-crystalline silicon) for a channel region is used. The P-Si TFT is manufactured by laser-annealing method of irradiating a whole surface of a substrate with laser beams and thereafter performing patterning.
JP 2012-114131 A discloses a thin film transistor comprising a gate insulating film formed so as to cover a gate electrode, a polysilicon film formed on the gate insulating film, a source electrode formed above one end of the polysilicon film, and a drain electrode formed, apart from the source electrode, above the other end of the polysilicon film opposed to the one end of the polysilicon film where the source electrode is formed, in which a degree of crystallinity of the polysilicon film gets smaller from the end of the polysilicon film where the source electrode or the drain electrode is formed toward a center portion of the polysilicon film where a source electrode or a drain electrode is not formed.